Amid what one public health expert said Friday is the worst flu outbreak in a decade, hospitals across the region have been doubling down on precautionary measures that include visitation restrictions on children and others at high risk for spreading the virus.

The measures come as emergency department visits throughout the state due to flu-related symptoms -- which, as of last week, had spiked to nearly 1 out of every 8 patients seen, according to data from the state Health Department -- are running at twice the pace that was being seen at this time last year.

With experts still unsure if this year's flu season has hit its peak, officials at the Centers for Disease Control and Prevention are continuing to advise common-sense measures such as frequent hand-washing, covering one's coughs and sneezes, and avoiding close contact with sick people to prevent the virus from spreading.

At Newton Medical Center and Hackettstown Medical Center, signs in the main lobbies direct visitors to kiosks with hand-sanitizer dispensers that they are instructed to use along with protective masks and gloves to wear when visiting sick patients.

The instructions also explicitly bar children and teens under 16 years old from visiting the maternity and pediatric wards and neonatal and pediatric intensive care units.

Dr. Donald Allegra, an infectious disease specialist at Newton Medical Center, said that although the virus so far has been kept from spreading inside the hospital, the visitation policy -- which he said is constantly being reviewed, and may even be further restricted if necessary -- will likely remain in effect until this year's flu epidemic begins to subside.

He estimates that that could entail at least "a couple of more weeks."

"We certainly want people to have access to their loved ones, but the reason we're concerned about children is you have issues of hygiene that are harder to maintain such as with a 3-year-old not washing his or her hands, blowing his nose, and just touching everything in sight," Allegra said.

This year's flu season, which normally runs from November to May, started somewhat slowly but picked up significantly in January.

Allegra said the spike is at least partly attributable to the fact that the flu vaccine administered at the start of the 2017-18 season has not been as effective as hoped against the H3N2 influenza virus subtype, which has since mutated into a different and more potent strain than the one included in this year's vaccine.

Flu viruses, by their very nature, can infect birds and mammals and are thus constantly mutating into different strains -- a process referred to by epidemiologists as "drift," which Allegra said has led to this year's flu season being the worst in a decade.

Every so often, he added, flu viruses undergo a major "shift" to what is essentially an entirely new virus. Such was the case 100 years ago, when a 1918 influenza pandemic -- the worst in history -- took the lives of between 50 million and 100 million people worldwide.

From swine flu to bird flu and others, these mutant viruses wreak havoc with mass vaccination programs intended to inhibit the spread of flu.

Still, Allegra said there are benefits to vaccination that transcend the statistical success at combating a particular strain in a given year.

"Even though the virus mutates year after year and we're always trying to play catch-up, people who get the vaccine every year tend to develop enhanced immunity against all variants of the disease and to do much better over the long term," Allegra said.

Additionally, he said, "Even if it isn't completely effective in preventing the disease, it does seem to ameliorate the symptoms and complications associated with it. And we know that if you get the vaccine, your chances of dying of influenza or being hospitalized or having a serious infection are much less than in those who don't get the vaccine."

Allegra said he would encourage anyone who has not been vaccinated this year, even at this late date, to consider doing so. He said that although the vaccine may take up to two weeks to produce the desired immune response, flu outbreaks can often extend into May.

Why flu season peaks in winter is a question that has long puzzled public health experts.

Traditionally, the thinking has been that people in winter spend more time in close quarters indoors, which facilitates the disease's spread among people whose immune systems may already be at less than peak efficiency due to lack of the sunlight necessary for boosting vitamin D and melatonin levels.

However, studies over the last decade suggest the virus itself is best able to survive in cold, dry conditions most commonly associated with winter.

The confluence of the flu and common cold, both of which are most prevalent in winter, sometimes is an additional source of confusion. Most typically, however, flu symptoms including fever and chills will come on abruptly whereas symptoms of the common cold occur more gradually.

"In simple terms, I generally divide it from above the neck to below the neck," Allegra said. "If you mainly have a stuffed nose, sore throat and head congestion, that's usually a cold -- but usually a cold won't keep you in bed."

On the other hand, "If you have muscle aches and pains, are miserable with a high fever and are confined to your bed, that's usually influenza. When you get the flu, you're really on your back and can barely get up without dizziness."

For young children and others with compromised immune systems -- a group that would include pregnant women, the elderly, and patients undergoing chemotherapy or steroid treatment -- getting prompt medical attention is critical, as Tamiflu and other antiviral medications typically are most effective when taken in the first 48 hours after contracting a virus.

"Tamiflu works by cutting down on the replication of the virus," Allegra said. "For an otherwise healthy person, the benefit may be marginal -- but for a person at risk of serious complications, it could be lifesaving."

Allegra said he also advises people falling into any of the high-risk groups to avoid crowded indoor areas where they may come into close contact with other sick people.

"We all have to keep living our lives, and if your son is playing basketball and has a tournament, I assume you're going to go to it," he said. "But if you have emphysema or heart disease or other health conditions, even if you've been vaccinated, I wouldn't recommend going to a Knick game or to a concert at Madison Square Garden."

Allegra said there are promising developments afoot that suggest better flu vaccines may be on the horizon in the next few years. He noted that a bill titled the Flu Vaccine Act, which has just been introduced by U.S. Sen. Edward Markey, D-Mass., is proposing to make available $200 million per year over the next five years toward the development of a better flu vaccine than current seasonal vaccines.

Allegra said the annual death toll of flu often goes unmentioned but remains a pressing public health problem.

"Although people with the most serious complications usually have another underlying medical condition, it's estimated that in the United States alone, we're seeing about 4,000 extra deaths per week during flu season," Allegra said. "We just have to invest the finances to develop a vaccine that will be more effective and permanent."

Eric Obernauer can also be contacted on Twitter: @EricObernNJH or by phone at 973-383-1213.